1. Field of the Invention
The present invention relates to the coupling of light from a light-emitting diode into at least one optical fiber. The apparatus in particular relates to a coupling-in apparatus for coupling light from a light-emitting diode into a fiber entry end of at least one optical fiber and to a light-source arrangement having a coupling-in apparatus of this type.
2. Description of the Related Art
There are optical apparatuses which require high-power light sources, but where the arrangement of the primary light source on the apparatus itself is not possible or desirable. One example of a apparatus of this type is a surgical microscope, which typically requires a high-power light source for illuminating the operating area. Since such a surgical microscope should limit the movement range of the doctor using the microscope as little as possible, the aim is to design surgical microscopes to be as compact as possible. One option for saving installation space inside the surgical microscope is to move the high-power light source into a region of the microscope body and to guide the light from the light source via an optical fiber or a fiber bundle into the illumination device of the microscope. Additionally, fans for cooling the high-power light source are typically necessary, which can result in vibrations which, if possible, should not be coupled into the surgical microscope. This is another aspect in respect of which it is advantageous to arrange the actual high-power light source at a distance from the surgical microscope and to guide the light into the illumination device of the surgical microscope using an optical fiber or a fiber bundle.
The high-power light sources used nowadays are increasingly high-power light-emitting diodes, because they have a higher efficiency for example as compared to xenon gas discharge lamps or halogen incandescent lamps and thus generate less heat. However, cooling has not yet become completely dispensible, and the problems relating to installation space also in principle remain, which is why the light from high-power LEDs is frequently transported to the site of use by way of optical fibers.
Today's fiber-coupled high-power light sources are frequently based on large high-power LED chips, on which an optical fiber is arranged using a butt coupling. In the case of such a butt coupling, the fiber entry end is moved as closely as possible to the luminous face of the LED in order to minimize optical losses in the air gap. A butt coupling is described in DE 10 2009 054 392 A1, for example.
Against this state of the art, it is an object of the present invention to provide an advantageous coupling-in apparatus for coupling light from a light-emitting diode into a fiber entry end. It is another object to provide an advantageous light-source arrangement having a light-emitting diode and at least one optical fiber, into which the light from the light-emitting diode is coupled.
The first object is achieved by a coupling-in apparatus according to claim 1, and the second object is achieved by a light-source arrangement according to claim 10. The dependent claims include advantageous configurations of the invention.